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2.5 V/3.3 V, 2-Bit, Individual Control Level Translator Bus Switch ADG3243
FEATURES 225 ps Propagation Delay through the Switch 4.5 Switch Connection between Ports Data Rate 1.5 Gbps 2.5 V/3.3 V Supply Operation Level Translation 3.3 V to 2.5 V 2.5 V to 1.8 V Small Signal Bandwidth 710 MHz 8-Lead SOT-23 Package APPLICATIONS 3.3 V to 2.5 V Voltage Translation 2.5 V to 1.8 V Voltage Translation Bus Switching Bus Isolation Hot Swap Hot Plug Analog Switch Applications FUNCTIONAL BLOCK DIAGRAM
A0 B0
BE0
A1
B1
BE1
GENERAL DESCRIPTION
PRODUCT HIGHLIGHTS
The ADG3243 is a 2.5 V or 3.3 V, 2-bit, 2-port digital switch with individual channel control. It is designed on a low voltage CMOS process, which provides low power dissipation yet gives high switching speed and very low on resistance. This allows the inputs to be connected to the outputs without additional propagation delay or generating additional ground bounce noise. The switches are enabled by means of the bus enable (BEx) input signal. This digital switch allows a bidirectional signal to be switched when ON. In the OFF condition, signal levels up to the supplies are blocked. This device is ideal for applications requiring level translation. When operated from a 3.3 V supply, level translation from 3.3 V inputs to 2.5 V outputs is allowed. Similarly, if the device is operated from a 2.5 V supply and 2.5 V inputs are applied, the device will translate the outputs to 1.8 V. This makes the device suited to applications requiring level translation between different supplies, such as converter to DSP/microcontroller interfacing.
1. 2. 3. 4. 5.
3.3 V or 2.5 V supply operation. Extremely low propagation delay through switch. 4.5 switches connect inputs to outputs. Level/voltage translation. Tiny SOT-23 package.
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Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective companies.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781/329-4700 www.analog.com Fax: 781/326-8703 (c) 2003 Analog Devices, Inc. All rights reserved.
ADG3243-SPECIFICATIONS1
Parameter Symbol DC ELECTRICAL CHARACTERISTICS Input High Voltage VINH VINH Input Low Voltage VINL VINL Input Leakage Current II OFF State Leakage Current IOZ ON State Leakage Current Maximum Pass Voltage VP CAPACITANCE3 A Port Off Capacitance B Port Off Capacitance A, B Port On Capacitance Control Input Capacitance SWITCHING CHARACTERISTICS 3 Propagation Delay A to B or B to A, t PD4 Propagation Delay Matching 5 Bus Enable Time BEx to A or B6 Bus Disable Time BEx to A or B6 Bus Enable Time BEx to A or B6 Bus Disable Time BEx to A or B6 Maximum Data Rate Channel Jitter DIGITAL SWITCH On Resistance
(VCC = 2.3 V to 3.6 V, GND = 0 V, all specifications TMIN to TMAX, unless otherwise noted.)
B Version Typ2 Max
Conditions VCC = 2.7 V to 3.6 V VCC = 2.3 V to 2.7 V VCC = 2.7 V to 3.6 V VCC = 2.3 V to 2.7 V 0 A, B VCC 0 A, B VCC VA/VB = VCC = 3.3 V, IO = -5 A VA/VB = VCC = 2.5 V, IO= -5 A f = 1 MHz f = 1 MHz f = 1 MHz f = 1 MHz CL = 50 pF, VCC = 3 V VCC = 3.0 V to 3.6 V VCC = 3.0 V to 3.6 V VCC = 2.3 V to 2.7 V VCC = 2.3 V to 2.7 V VCC = 3.3 V; VA/VB = 2 V VCC = 3.3 V; VA/VB = 2 V VCC = 3 V, VA = 0 V, IBA = 8 mA VCC = 3 V, VA = 1.7 V, IBA = 8 mA VCC = 2.3 V, VA = 0 V, IBA = 8 mA VCC = 2.3 V, VA = 1 V, IBA = 8 mA VCC = 3 V, VA = 0 V, IA = 8 mA
Min 2.0 1.7
Unit V V V V A A A V V pF pF pF pF
2.0 1.5
0.01 0.01 0.01 2.5 1.8 3.5 3.5 7 4
0.8 0.7 1 1 1 2.9 2.1
CA OFF CB OFF CA, CB ON CIN tPHL, tPLH tPZH, tPZL tPHZ, tPLZ tPZH, tPZL tPHZ, tPLZ
1 1 1 1
3.2 3 3 2.5 1.5 45 4.5 12 5 9 0.1
225 5 4.6 4 4 3.4
ps ps ns ns ns ns Gbps ps p-p V A A
RON
On Resistance Matching POWER REQUIREMENTS VCC Quiescent Power Supply Current Increase in ICC per Input7
RON
8 28 9 18 0.5 3.6 1 8
2.3 ICC ICC Digital Inputs = 0 V or V CC VCC = 3.6 V, BE0 = 3.0 V, BE1 = VCC or GND 0.01 0.15
NOTES 1 Temperature range is as follows: B Version: -40C to +85C. 2 Typical values are at 25C, unless otherwise stated. 3 Guaranteed by design, not subject to production test. 4 The digital switch contributes no propagation delay other than the RC delay of the typical R ON of the switch and the load capacitance when driven by an ideal voltage source. Since the time constant is much smaller than the rise/fall times of typical driving signals, it adds very little propagation delay to the system. Propagation delay of the digital switch when used in a system is determined by the driving circuit on the driving side of the switch and its interaction with the load on the driven side. 5 Propagation delay matching between channels is calculated from the on resistance matching and load capacitance of 50 pF. 6 See Timing Measurement Information section. 7 This current applies to the control pin BEx only. The A and B ports contribute no significant ac or dc currents as they transition. Specifications subject to change without notice.
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ADG3243
ABSOLUTE MAXIMUM RATINGS*
(TA = 25C, unless otherwise noted.)
PIN CONFIGURATION 8-Lead SOT-23
BE0 1 A0 2
3 8
VCC to GND . . . . . . . . . . . . . . . . . . . . . . . . . -0.5 V to +4.6 V Digital Inputs to GND . . . . . . . . . . . . . . . . . -0.5 V to +4.6 V DC Input Voltage . . . . . . . . . . . . . . . . . . . . . -0.5 V to +4.6 V DC Output Current . . . . . . . . . . . . . . . . . 25 mA per Channel Operating Temperature Range Industrial (B Version) . . . . . . . . . . . . . . . . -40C to +85C Storage Temperature Range . . . . . . . . . . . . -65C to +150C Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . 150C JA Thermal Impedance . . . . . . . . . . . . . . . . . . . . . 206C/ Lead Temperature, Soldering (10 sec) . . . . . . . . . . . . . 300C IR Reflow, Peak Temperature (<20 sec) . . . . . . . . . . . . 235C
*Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those listed in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Only one absolute maximum rating may be applied at any one time.
VCC BE1
ADG3243
7
TOP VIEW 6 B0 A1 (Not to Scale) 5 B1 GND 4
PIN FUNCTION DESCRIPTIONS
Pin No. 1 2 3 4 5 6 7 8
Mnemonic BE0 A0 A1 GND B1 B0 BE1 VCC
Description Bus Enable (Active Low) Port A0, Input or Output Port A1, Input or Output Ground Reference Port B1, Input or Output Port B0, Input or Output Bus Enable (Active Low) Positive Power Supply Voltage
Table I. Truth Table
BEx L H
Function Ax = Bx, 3.3 V to 2.5 V/2.5 V to 1.8 V Level Shifting Disconnect
ORDERING GUIDE
Model ADG3243BRJ-R2 ADG3243BRJ-REEL ADG3243BRJ-REEL7
Temperature Range -40C to +85C -40C to +85C -40C to +85C
Package Description SOT-23 (Small Outline Transistor Package) SOT-23 (Small Outline Transistor Package) SOT-23 (Small Outline Transistor Package)
Package RJ-8 RJ-8 RJ-8
Branding SFA SFA SFA
CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although the ADG3243 features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality.
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ADG3243
TERMINOLOGY VCC GND VINH VINL II IOZ IOL VP RON RON CX OFF CX ON CIN ICC ICC tPLH, tPHL tPZH, tPZL tPHZ, tPLZ Positive Power Supply Voltage. Ground (0 V) Reference. Minimum Input Voltage for Logic 1. Maximum Input Voltage for Logic 0. Input Leakage Current at the Control Inputs. OFF State Leakage Current. It is the maximum leakage current at the switch pin in the OFF state. ON State Leakage Current. It is the maximum leakage current at the switch pin in the ON state. Maximum Pass Voltage. The maximum pass voltage relates to the clamped output voltage of an NMOS device when the switch input voltage is equal to the supply voltage. Ohmic Resistance Offered by a Switch in the ON State. It is measured at a given voltage by forcing a specified amount of current through the switch. ON Resistance Match between Any Two Channels, i.e., RON max - RON min. OFF Switch Capacitance. ON Switch Capacitance. Control Input Capacitance. This consists of BEx. Quiescent Power Supply Current. This current represents the leakage current between the VCC and ground pins. It is measured when all control inputs are at a logic high or low level and the switches are OFF. Extra power supply current component for the EN control input when the input is not driven at the supplies. Data Propagation Delay through the Switch in the ON State. Propagation delay is related to the RC time constant RON x CL, where CL is the load capacitance. Bus Enable Times. These are the times taken to cross the VT voltage at the switch output when the switch turns on in response to the control signal, BEx. Bus Disable Times. This is the time taken to place the switch in the high impedance OFF state in response to the control signal. It is measured as the time taken for the output voltage to change by V from the original quiescent level, with reference to the logic level transition at the control input. (Refer to Figure 3 for enable and disable times.) Maximum Rate at which Data Can Be Passed through the Switch. Peak-to-Peak Value of the Sum of the Deterministic and Random Jitter of the Switch Channel.
Max Data Rate Channel Jitter
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Typical Performance Characteristics-ADG3243
40 35 30
RON ( ) RON ( )
40
20
TA = 25 C VCC = 2.3V
TA = 25 C
VCC = 3V
VCC = 3.3V
35 30 25
15
25 VCC = 3.3V 20 15 10 5 0 VCC = 3.6V
RON ( )
VCC = 2.5V 20 15 VCC = 2.7V 10 5
10 85 C
5
25 C 40 C
0
0.5
1.0
2.0 1.5 VA/VB (V)
2.5
3.0
3.5
0
0
0.5
1.0
1.5 2.0 VA/VB (V)
2.5
3.0
0
0
0.5
1.0 VA/VB (V)
1.5
2.0
TPC 1. On Resistance vs. Input Voltage
TPC 2. On Resistance vs. Input Voltage
TPC 3. On Resistance vs. Input Voltage for Different Temperatures
15 VCC = 2.5V
3.0 2.5 TA = 25 C IO = -5 A
2.5
VCC = 3.6V
TA = 25 C IO = -5 A 2.0
VCC = 2.7V
VOUT (V)
VOUT (V)
10 RON ( ) 85 C
2.0 1.5
VCC = 3.3V VCC = 3V
1.5
VCC = 2.5V VCC = 2.3V
1.0 5 40 C 25 C 0.5
0.5 1.0
0
0
0.5 VA/VB (V)
1.0
1.2
0
0
0 0.5 1.0 2.0 1.5 VA/VB (V) 2.5 3.0 3.5
0
0.5
1.0
1.5 2.0 VA/VB (V)
2.5
3.0
TPC 4. On Resistance vs. Input Voltage for Different Temperatures
TPC 5. Pass Voltage vs. VCC
TPC 6. Pass Voltage vs. VCC
500 450 400 350
VOUT (V)
TA = 25 C
3.0 2.5 TA = 25 C VA = 0V BEx = 0
3.0 2.5 TA = 25 C VA = VCC BEx = 0 VCC = 3.3V
ICC ( A)
VOUT (V)
300 250 200 150 100 50 0 0 5
VCC = 3.3V
2.0
2.0
1.5
1.5
VCC = 3.3V
1.0
1.0
VCC = 2.5V
VCC = 2.5V
0.5 0 0 0.02 VCC = 2.5V 0.04 0.06 IO (A) 0.08 0.10
0.5 0 -0.10
10 15 20 25 30 35 40 45 50 ENABLE FREQUENCY (MHz)
-0.08
-0.06 -0.04 IO (A)
-0.02
0
TPC 7. ICC vs. Enable Frequency
TPC 8. Output Low Characteristic
TPC 9. Output High Characteristic
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ADG3243
0 -0.2 -0.4 -0.6 TA = 25 C ON OFF CL = InF 0 -2 TA = 25 C VCC = 3.3V/2.5V VIN = 0dBm N/W ANALYZER: RL = RS = 50
0 -10 -20 TA = 25 C VCC = 3.3V/2.5V VIN = 0dBm N/W ANALYZER RL = RS = 50
ATTENUATION (dB)
ATTENUATION (dB)
-4 -6 -8
-30 -40 -50 -60 -70 -80
QINJ (pC)
-0.8 -1.0 -1.2 -1.4 -1.6 -1.8 -2.0 0
VCC = 2.5V
-10 VCC = 3.3V -12 -14 0.03 0.1 1 10 100 FREQUENCY (MHz) 1000
-90 -100 0.03 0.1 1.0 10 100 FREQUENCY (MHz) 1000
0.5
1.0
1.5 2.0 VA/VB (V)
2.5
3.0
TPC 10. Charge Injection vs. Source Voltage
0 TA = 25 C -10 VCC = 3.3V/2.5V VIN = 0dBm -20 N/W ANALYZER: -30 RL = RS = 50
TPC 11. Bandwidth vs. Frequency
TPC 12. Crosstalk vs. Frequency
4.0 3.5 3.0 2.5 2.0 1.5 1.0 ENABLE DISABLE VCC = 3.3V ENABLE DISABLE
100 VCC = 3.3V 90 V = 1.5V p-p IN 80 20dB ATTENUATION
ATTENUATION (dB)
-50 -60 -70 -80 -90
TIME (ns)
-40
JITTER (ps p-p)
VCC = 2.5V
70 60 50 40 30 20
0.5 0 -40
10
-100 0.1
1
100 10 FREQUENCY (MHz)
1000
-20
0 20 40 60 TEMPERATURE ( C)
80
0 0.5
0.7
0.9 1.1 1.3 1.5 1.7 DATA RATE (Gbps)
1.9
TPC 13. Off Isolation vs. Frequency
TPC 14. Enable/Disable Time vs. Temperature
TPC 15. Jitter vs. Data Rate; PRBS 31
100 95 VCC = 3.3V 90 V = 1.5V p-p IN 85 20dB ATTENUATION 80 75 70 65 60 55 % EYE WIDTH = ((CLOCK PERIOD - JITTER p-p)/CLOCK PERIOD) 100% 0.7 0.9 1.1 1.3 1.5 1.7 DATA RATE (Gbps) 1.9
EYE WIDTH (%)
50mV/DIV 200ps/DIV
VCC = 3.3V VIN = 1.5V p-p
50 0.5
20dB ATTENUATION TA = 25 C
20mV/DIV 200ps/DIV
VCC = 2.5V VIN = 1.5V p-p
20dB ATTENUATION TA = 25 C
TPC 16. Eye Width vs. Data Rate; PRBS 31
TPC 17. Eye Pattern; 1.5 Gbps, VCC = 3.3 V, PRBS 31
TPC 18. Eye Pattern; 1.244 Gbps, VCC = 2.5 V, PRBS 31
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ADG3243
TIMING MEASUREMENT INFORMATION Test Conditions
For the following load circuit and waveforms, the notation that is used is VIN and VOUT where
Symbol RL V CL VT
VCC = 3.3 V 500 300 50 1.5
0.3 V
VCC = 2.5 V 500 150 30 0.9
0.2 V
Unit mV pF V
VIN = VA and VOUT = VB or VIN = VB and VOUT = VA
VCC SW1 2 VCC
VIN PULSE GENERATOR RT DUT
VOUT
RL
GND
Table II. Switch Position
Test
CL RL
S1 2 x VCC GND
DISABLE VINH VT 0V
tPLZ, tPZL tPHZ, tPZH
ENABLE CONTROL INPUT BEx
NOTES PULSE GENERATOR FOR ALL PULSES: tR 2.5ns, tF 2.5ns, FREQUENCY 10MHz. CL INCLUDES BOARD, STRAY, AND LOAD CAPACITANCES. RT IS THE TERMINATION RESISTOR, SHOULD BE EQUAL TO ZOUT OF THE PULSE GENERATOR.
Figure 1. Load Circuit
VIH CONTROL INPUT BEx VT
tPZL
VOUT SW1 @ 2VCC VCC VT
tPLZ
VCC VL + V VL
VIN = 0V
tPZH
VIN = VCC VOUT SW1 @ GND VT 0V
tPHZ
VH VH - V 0V
tPLH
VOUT
tPLH
0V VH VT VL
Figure 2. Propagation Delay
Figure 3. Enable and Disable Times
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ADG3243
BUS SWITCH APPLICATIONS Mixed Voltage Operation, Level Translation 2.5 V to 1.8 V Translation
Bus switches can provide an ideal solution for interfacing between mixed voltage systems. The ADG3243 is suitable for applications where voltage translation from 3.3 V technology to a lower voltage technology is needed. This device can translate from 2.5 V to 1.8 V or bidirectionally from 3.3 V directly to 2.5 V. Figure 4 shows a block diagram of a typical application in which a user needs to interface between a 3.3 V ADC and a 2.5 V microprocessor. The microprocessor may not have 3.3 V tolerant inputs, therefore placing the ADG3243 between the two devices allows the devices to communicate easily. The bus switch directly connects the two blocks, thus introducing minimal propagation delay, timing skew, or noise.
3.3V 3.3V 2.5V
When VCC is 2.5 V and the input signal range is 0 V to VCC, the maximum output signal will, as before, be clamped to within a voltage threshold below the VCC supply. In this case, the output will be limited to approximately 1.8 V, as shown in Figure 8.
2.5V
2.5V
ADG3243
1.8V
Figure 7. 2.5 V to 1.8 V Voltage Translation
ADG3243
VOUT
2.5V MICROPROCESSOR
2.5V SUPPLY 1.8V
SWITCH OUTPUT
3.3V ADC
Figure 4. Level Translation between a 3.3 V ADC and a 2.5 V Microprocessor
3.3 V to 2.5 V Translation
0V
When VCC is 3.3 V and the input signal range is 0 V to VCC, the maximum output signal will be clamped to within a voltage threshold below the VCC supply.
3.3V
SWITCH INPUT
VIN 2.5V
Figure 8. 2.5 V to 1.8 V Voltage Translation
Bus Isolation
3.3V
2.5V
ADG3243
2.5V 2.5V
A common requirement of bus architectures is low capacitance loading of the bus. Such systems require bus bridge devices that extend the number of loads on the bus without exceeding the specifications. Because the ADG3243 is designed specifically for applications that do not need drive yet require simple logic functions, it solves this requirement. The device isolates access to the bus, thus minimizing capacitance loading.
LOAD A LOAD C
Figure 5. 3.3 V to 2.5 V Voltage Translation
In this case, the output will be limited to 2.5 V, as shown in Figure 6. This device can be used for translation from 2.5 V to 3.3 V devices and also between two 3.3 V devices.
VOUT 3.3V SUPPLY 2.5V
SWITCH OUTPUT
BUS/ BACKPLANE LOAD B LOAD D
BUS SWITCH LOCATION
Figure 9. Location of Bus Switched in a Bus Isolation Application
Hot Plug and Hot Swap Isolation
0V
SWITCH INPUT
VIN 3.3V
The ADG3243 is suitable for hot swap and hot plug applications. The output signal of the ADG3243 is limited to a voltage that is below the VCC supply, as shown in Figures 6 and 8. Therefore the switch acts like a buffer to take the impact from hot insertion, protecting vital and expensive chipsets from damage. In hot plug applications, the system cannot be shut down when new hardware is being added. To overcome this, a bus switch can be positioned on the backplane between the bus devices and the hot plug connectors. The bus switch is turned off during hot plug. Figure 10 shows a typical example of this type of application.
Figure 6. 3.3 V to 2.5 V Voltage Translation
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ADG3243
PLUG-IN CARD (1) CARD I/O CPU
switches. The bus switches are positioned on the hot swap card between the connector and the devices. During hot swap, the ground pin of the hot swap card must connect to the ground pin of the backplane before any other signal or power pins.
Analog Switching
RAM
ADG3243
ADG3243
PLUG-IN CARD (2)
CARD I/O
BUS
Figure 10. ADG3243 in a Hot Plug Application
Bus switches can be used in many analog switching applications, for example, video graphics. Bus switches can have lower on resistance, smaller ON and OFF channel capacitance, and thus improved frequency performance than their analog counterparts. The bus switch channel itself, consisting solely of an NMOS switch, limits the operating voltage (see TPC 1 for a typical plot), but in many cases, this does not present an issue.
High Impedance during Power-Up/Power-Down
There are many systems, such as docking stations, PCI boards for servers, and line cards for telecommunications switches, that require the ability to handle hot swapping. If the bus can be isolated prior to insertion or removal, there is more control over the hot swap event. This isolation can be achieved using bus
To ensure the high impedance state during power-up or powerdown, BEx should be tied to VCC through a pull-up resistor; the minimum value of the resistor is determined by the currentsinking capability of the driver.
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ADG3243
OUTLINE DIMENSIONS 8-Lead Small Outline Transistor Package [SOT-23] (RJ-8)
Dimensions shown in millimeters
2.90 BSC
8
7
6
5
1.60 BSC
1 2 3 4
2.80 BSC
PIN 1 0.65 BSC 1.30 1.15 0.90 1.95 BSC
1.45 MAX 0.38 0.22
0.22 0.08 8 4 0
0.15 MAX
SEATING PLANE
0.60 0.45 0.30
COMPLIANT TO JEDEC STANDARDS MO-178BA
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C04310-0-8/03(0)

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